1. Field of Invention
The present invention relates to automatic transmission systems and, more particularly to an improved Manual Valve for Chrysler 40RH, 42RH, 42RE, 46RH and 46RE transmissions (hereinafter xe2x80x9cChrysler transmissionsxe2x80x9d).
Automatic transmission systems of the prior art have a hydraulic circuit sub-system which includes at least a hydraulic pump, a valve body having fluid conducting passages or circuits, input and exhaust ports formed within the fluid circuits, and a plurality of so-called xe2x80x9cspoolxe2x80x9d valves comprised of modified pistons which alternately open and close the ports to regulate the flow and pressure of automatic transmission fluid (hereinafter xe2x80x9cATFxe2x80x9d) within the fluid circuits to actuate different components of the transmission. It will be understood that in describing hydraulic fluid circuits, ATF usually changes names when it passes through an orifice or control valve in a specific circuit.
The Manual Valve in an automatic transmission is a spool valve connected by linkage or cable to the shift lever inside the passenger compartment. The Manual Valve, which is also connected to the manual lever on the side of the transmission, directs fluid flow within the transmission to provide the correct type of operation for the selected gear range. For example, when Neutral or Park are selected, ATF is directed to pressure reducing circuits and to exhaust sending line pressure back to the transmission sump such that no apply devices are engaged. When Reverse is selected, the pressure reducing circuits and exhaust port are blocked sending line pressure to apply reverse gear. When Drive is selected, ATF is directed to the Drive control circuits including the forward clutch and the governor feed circuit to operate the transmission.
Vehicles utilizing the aforementioned Chrysler transmissions typically do not deliver sufficient ATF to the torque converter/cooler charge circuits when the transmission is in Park. This presents a problem in that the torque converter must be filled with ATF to engage the transmission. Insufficient ATF level in the torque converter results in delayed engagement upon shifting into Drive or Reverse. Further, torque converter bushing failure may eventually occur.
2. Description of Related Prior Art
Various efforts have been made in the transmission parts aftermarket industry to alter the configuration of the OEM manual valve in the aforementioned Chrysler transmissions to eliminate the delayed engagement problem upon shifting from Park into Drive and/or Reverse gear ranges as described hereinabove. For example, aftermarket manual valves developed by TransGo, Inc., Merced, Calif.; Superior Transmission Parts, Inc., Tallahassee, Fla.; and Red-Butt Engineering, have been marketed for this purpose. However, such previous reconfigurations of the Chrysler manual valve have focused primarily on blocking the flow of ATF to exhaust when the Park gear range is selected to generate an overall increase in line pressure thereby actuating the Pressure Regulator Valve to increase ATF feed to the torque converter/cooler charge circuits without adequate consideration for other apply devices affected by the line pressure increase.
More particularly, such aftermarket manual valves have failed to control the resulting increased line pressure to the Pressure Regulator Valve at consistent levels to prevent ATF feed to and partial actuation (i.e. dragging) of the forward clutch while in Park gear range. Thus, installation of the aforementioned aftermarket manual valves during maintenance service and/or transmission overhaul has resulted in erratic line pressure levels and subsequent burnout of the forward clutch.
Further, the aftermarket manual valves described hereinabove typically require that physical alteration of the manual valve and/or valve body by the service technician be performed prior to installation in the Chrysler transmissions producing inconsistent results.
Thus, the present invention has been developed to resolve these problems and other shortcomings of the prior art.
Accordingly, the present invention is an improved Manual Valve, which is a direct replacement for the original equipment manufacture (hereinafter xe2x80x9cOEMxe2x80x9d) Manual Valve that is standard equipment on many transmissions made available on Chrysler rear wheel drive vehicles and which will be referred to throughout this specification.
The Manual Valve of the present invention has been redesigned to change the configuration of the control diameters or lands such that when Park is selected, ATF flow to the Park pressure reducing circuits is blocked thereby increasing ATF pressure in the Throttle Valve (hereinafter xe2x80x9cTVxe2x80x9d) circuit, which controls changes in the position of the Pressure Regulator Valve. This elevated fluid pressure in the TV circuit actuates the Pressure Regulator Valve opening the torque converter/cooler feed circuits to charge the torque converter while in Park. Thus, delayed engagement of the transmission upon shifting into Drive or Reverse is eliminated and the increased ATF flow in the torque converter/cooler charge circuits provides additional lubrication and reduces torque converter bushing failure.
In addition, the present Manual Valve also includes an integrally formed ATF control orifice and an alternate exhaust channel, which function to meter the exhaust of ATF via the alternate exhaust channel when the Park gear range is selected thereby generating a predetermined backpressure in the TV circuit and imparting improved stability to the Pressure Regulator Valve to prevent slippage and premature wear of the forward clutch.
Further, a Reverse fluid metering diameter or land has been added to the present Manual Valve to reduce the initial ATF pressure applied to the Reverse servo piston and Low/Reverse clutch band when Reverse gear is selected to prevent damage thereto, which is also problematic in the Chrysler transmissions.
Thus, it is an object of the present invention to provide an improved Manual Valve which functions to limit the flow of ATF to exhaust when the Park gear range is selected thereby increasing hydraulic fluid pressure to the Pressure Regulator Valve and opening the torque converter/cooler charge circuits to charge the torque converter.
Another object of the present invention is to provide an improved Manual Valve having an ATF control orifice disposed in fluid communication with an alternate exhaust channel, which functions to meter the exhaust of ATF via the alternate exhaust channel when the Park gear range is selected thereby generating a predetermined backpressure in the TV circuit and imparting improved stability to the Pressure Regulator Valve.
Another object of the present invention is to provide an improved Manual Valve including a Reverse fluid metering land to minimize the initial fluid shock applied to the Reverse servo piston and Low/Reverse clutch band when Reverse gear is selected to prevent damage thereto.
Other features and technical advantages of the present invention will become apparent from a study of the following description and the accompanying drawings.